1. Field of the Invention
The present invention relates to a semiconductor device with bare chips mounted on a support substrate.
2. Related Art
A flash memory is widely used as a storage device of various kinds of electronics because it is freely rewritable and can hold data without a supply voltage. Since the flash memory can read/reproduce data without mechanical parts such as an optical pickup or a magnetic head, the sizes of the electronics can be smaller, and electrical power consumption can also be reduced. Further, since the flash memory has no mechanical parts, product durability can be improved, and cost reduction can also be achieved. In view of such a background, the flash memory is expected to be more and widely used as a replacement of a large capacity storage device such as a MD or a HDD.
However, since the flash memory is limited by the wiring rule width, its storage capacity cannot be increased rapidly. Accordingly, there is an approach for housing a plurality of flash memory chips formed on a wafer (hereinafter simply referred to as chips) in one package to increase the storage capacity.
It is not desirable to laterally align the chips for packaging, because overall size of the package becomes larger. In order to reduce overall size of the package, for example, it is considered that the chips are arranged on both sizes of a support substrate. The pads of the chips are connected to inner leads via bonding wires. However, since the bonding wires trace an arc, the chips need a height for the bonding wires. Especially, when the chips are arranged on both sides of the support substrate, the bonding wires have to also be arranged on the both sides of the chips. Therefore, it will be difficult to satisfy the limitation in the height direction.
An approach for lowering the height of the bonding wire is known (See; Japanese Patent Laid-Open No. 09-51011). However, even if a technology such as Japanese Patent Laid-Open No. 09-51011 is used to mount chips on both sides of a support substrate, at most two chips can be built in one package, thereby, it is not possible to significantly increase the storage capacity.